WO1999004488A1 - Procede servant a creer un dispositif a ondes acoustiques de surface sur du quartz - Google Patents

Procede servant a creer un dispositif a ondes acoustiques de surface sur du quartz Download PDF

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Publication number
WO1999004488A1
WO1999004488A1 PCT/US1998/014675 US9814675W WO9904488A1 WO 1999004488 A1 WO1999004488 A1 WO 1999004488A1 US 9814675 W US9814675 W US 9814675W WO 9904488 A1 WO9904488 A1 WO 9904488A1
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WO
WIPO (PCT)
Prior art keywords
crystal
quartz
approximately
lambda
value ranging
Prior art date
Application number
PCT/US1998/014675
Other languages
English (en)
Inventor
Benjamin P. Abbott
Original Assignee
Sawtek Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sawtek Inc. filed Critical Sawtek Inc.
Priority to AU84883/98A priority Critical patent/AU8488398A/en
Publication of WO1999004488A1 publication Critical patent/WO1999004488A1/fr

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02818—Means for compensation or elimination of undesirable effects
    • H03H9/02881—Means for compensation or elimination of undesirable effects of diffraction of wave beam
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02551—Characteristics of substrate, e.g. cutting angles of quartz substrates

Definitions

  • the invention relates to a surface acoustic wave (SAW) device and, more particularly, to a device having a quartz crystal substrate with a predetermined crystalline orientation for causing a surface acoustic wave to propagate along a predetermined crystalline axis of the substrate.
  • SAW surface acoustic wave
  • the invention relates to a surface acoustic wave (SAW) device and, more specifically, to a device having a quartz crystal substrate with a predetermined crystalline orientation for causing a surface acoustic wave to propagate along a predetermined crystalline axis of the substrate.
  • This invention relates to an optimal surface acoustic wave orientation on single crystal silicon dioxide or Si ⁇ 2, commonly referred to as quartz.
  • SAW devices are currently used as bandpass filters, resonators, delay lines, and convolvers, in a broad range of RF and IF applications such as wireless, cellular communication, and cable TV. Any piezoelectric crystal may be used to produce substrates for the construction of SAW devices.
  • a high velocity is desirable for high frequency devices, because the device geometry patterns are larger and, therefore, the devices are easier to fabricate.
  • a low velocity is usually desirable because the device size is smaller, resulting in lower device and packaging costs.
  • the desired value for k 2 is often set by the desired bandwidth of the SAW device. Large values of k 2 are well suited for broad bandwidth devices and lower values of k 2 for narrow bandwidth devices. Quartz is well suited for narrow bandwidth applications, lithium niobate for broad bandwidths, and lithium tantalate for moderate bandwidths.
  • the TCD should be as low as possible, and ideally zero.
  • TCD, k 2 , and PFA which are essentially the same as those for ST-quartz, and at the same time a diffraction coefficient, gamma, at or near the optimal value of -1.0.
  • One preferred embodiment of the present invention includes a device which contains a quartz substrate, on the surface of which input and output interdigital transducers (IDTs) are placed.
  • the surface of the quartz substrate is perpendicular to axis Z', the electrodes of the IDTs are perpendicular to axis X' and are parallel to axis Y'.
  • Axes X ⁇ Y', and Z' are defined by Euler angles with respect to crystal axes X, Y, and Z of the quartz crystal. Using Euler angles (lambda, mu, theta), a unique substrate orientation is defined. Angle lambda is in the range from -5° to 5°; angle mu in the range from 37° to 46°; and angle theta in the range from 20° to 26°.
  • FIG. 1 is a perspective view of a SAW device illustrating interdigital transducers (IDTs) located on a quartz substrate surface, and a power flow angle, PFA ⁇ ;
  • FIG. 2 diagrammatically illustrates substrate axes X', Y', and Z' and crystal axes X, Y, and Z along with first, second, and third Euler angles lambda, mu, and theta describing relative orientation of X, Y, and Z to X', Y', and Z', wherein X 1 is defined as a direction of SAW propagation;
  • FIGS. 3A-3C illustrate the dependence of the several SAW performance parameters including SAW velocity, k 2 , PFA, gamma, and TCD on the direction of propagation for a quartz substrate defined by the Euler angles (0°, 42°, theta), for theta between 0° and 30°;
  • FIG. 4 illustrates the dependence of the PFA on the third Euler angle, theta in a range of 0° to 30°.
  • the multiple curves result from varying the second Euler angle, mu, from 37° to 46° in increments of 1 °;
  • FIG. 7 is a plan view of a SAW device illustrating interdigital transducers (IDTs) in a tapered alignment located on a quartz substrate surface.
  • IDTs interdigital transducers
  • one preferred embodiment of the present invention includes a SAW device 10 which contains a quartz substrate 12 on the surface 14 of which an input interdigital transducer 16 and an output interdigital transducer 18 (IDT) are placed.
  • SAW device 10 which contains a quartz substrate 12 on the surface 14 of which an input interdigital transducer 16 and an output interdigital transducer 18 (IDT) are placed.
  • IDT input interdigital transducer
  • axes X', Y ⁇ and Z' are defined by Euler angles, (lambda, mu, theta), with respect to crystal axes X, Y, and Z of the quartz substrate 12.
  • angle lambda is in the range -5° to 5°; angle mu in the range 37 ° to 46°; and angle theta in the range 20° to 26°.
  • the crystal cut provides near simultaneous optimization of three critical SAW propagation parameters and a favorable value of a fourth parameter.
  • This fourth parameter is the coupling constant, k 2 , which varies between 0.15% and 0.18% as compared to 0.12% for ST-quartz crystal.
  • the three SAW propagation parameters are the PFA, gamma, and TCD, which as earlier described, are the power flow angle, the diffraction coefficient, and the temperature coefficient of delay, respectively.
  • PFA is also known as ⁇ , the beam steering angle, and is the angle between the SAW wave vector, which is generally normal to the tap electrodes 20, 22 as illustrated again with reference to
  • FIG. 1 and the direction of power flow.
  • the PFA would be zero.
  • FIGS. 3A-3C illustrate the dependence of the various SAW performance parameters such as SAW velocity, k 2 , PFA, gamma, and TCD on the direction of propagation for a quartz substrate defined by the Euler angles (0°, 42°, theta), for theta ranging from 0° to 30°.
  • a near optimal point can be seen for theta approximately equal to 22.5°.
  • the gamma data is scaled by 10 (1 + gamma) for convenience in viewing PFA and TCD.
  • FIG. 4 illustrates the dependence of the PFA on the third Euler angle, theta, in a range of 0° to 30°.
  • the multiple curves in FIG. 4 result from varying the second Euler angle, mu, from 37° to 46° in 1 ° increments. For each value of mu, there exists a value of theta for which the PFA is exactly zero.
  • FIG. 5 illustrates the value of theta at which the PFA in FIG. 4 equals zero for mu in the range of 37° to 46°.
  • SAW performance parameters SAW velocity, K 2 , TCD, and gamma
  • the optimal choice of angles would be dependent upon the application, choice of TCD, or slight variations in one or more of the three parameters, TCD, PFA, or gamma. This is the reason for the spread of angles disclosed herein.
  • one preferred embodiment of the present invention includes the SAW device 10 containing the quartz substrate 12, and IDTs 16, 18 and reflecting electrodes 24, 26.
  • the axis Z' is normal to the substrate surface 14
  • the axis X' is normal to electrodes 20, 22,
  • the Y' axis is parallel to the electrodes 20, 22.
  • lambda is the angle between crystal axis X and auxiliary axis X", which is the axis of rotation of the plane XY (up to required orientation of the substrate surface).
  • mu is the angle between axis Z and the normal Z' to the substrate surface 14.
  • theta is the angle between axis X" and axis X', and as earlier described X' is perpendicular to the electrodes 20, 22 of IDTs 16, 18, respectively.
  • the beam spreading is improved without substantial and within acceptable degradation of the TCD, PFA, or k 2 as compared to prior works on quartz, such as ST-quartz.
  • TCD time domain complementary metal-oxide-semiconductor
  • PFA pulse width-to-pass filter
  • k 2 k 2-to-pass filter
  • the above described propagation parameters are particularly advantageous for application to tapered SAW devices 30 as illustrated with reference to FIG. 7.
  • the SAW device 30 includes tapered transducers 32 having interdital electrodes 34.
  • the electrodes 34 have a tapered alignment, wherein the periodicity of electrodes 34 changes along a direction 36 generally orthogonal to an acoustic wave axis of propagation 38 through the transducer.
  • the axis of propagation 38 is defined by the crystal orientation Euler angle theta.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

Substrat monocristallin en quartz (12) présentant une étendue déterminée d'angles d'Euler servant à effectuer l'orientation du substrat et du quartz afin d'améliorer le traitement de signaux pour les dispositifs à ondes acoustiques de surface (SAW) (10). Quand on applique une tension à un transducteur interdigital d'entrée (IDT) du dispositif (SAW) (10), une onde acoustique de surface est générée dans le substrat en quartz (12). Cette onde acoustique de surface se propage dans un sens généralement perpendiculaire aux électrodes (20) du IDT (16). On définit les sens de propagation des ondes et de coupe du quartz afin de limiter les effets préjudiciables de la diffraction sur les dispositifs SAW (10). Ceci permet de limiter les distorsions de réponse de fréquence et les augmentations de pertes d'insertion dues à la diffraction, tout en maintenant une stabilité correcte à la température et un angle d'écoulement à basse puissance.
PCT/US1998/014675 1997-07-16 1998-07-15 Procede servant a creer un dispositif a ondes acoustiques de surface sur du quartz WO1999004488A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU84883/98A AU8488398A (en) 1997-07-16 1998-07-15 An optimal cut for saw devices on quartz

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US5265897P 1997-07-16 1997-07-16
US60/052,658 1997-07-16

Publications (1)

Publication Number Publication Date
WO1999004488A1 true WO1999004488A1 (fr) 1999-01-28

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PCT/US1998/014675 WO1999004488A1 (fr) 1997-07-16 1998-07-15 Procede servant a creer un dispositif a ondes acoustiques de surface sur du quartz

Country Status (3)

Country Link
US (1) US6031315A (fr)
AU (1) AU8488398A (fr)
WO (1) WO1999004488A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6031315A (en) * 1997-07-16 2000-02-29 Sawtek Inc. Optimal cut for saw devices on quartz
WO2004004119A1 (fr) * 2002-06-26 2004-01-08 Lg Innotek Co.,Ltd Substrat monocristallin et procede de decoupage de celui-ci
WO2008046393A1 (fr) * 2006-10-16 2008-04-24 Epcos Ag Composant électroacoustique
DE102007051314A1 (de) * 2007-10-26 2009-04-30 Epcos Ag Elektroakustisches Bauelement

Families Citing this family (10)

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FR2785473B1 (fr) * 1998-10-30 2001-01-26 Thomson Csf Filtre faibles pertes a ondes acoustiques de surface sur substrat de quartz de coupe optimisee
US6791236B1 (en) 2000-10-11 2004-09-14 Yuri Abramov Method utilizing the saw velocity dispersion effect for weighting by shaping the electrode fingers of a saw interdigital transducer and apparatus produced thereby
JP2002237724A (ja) * 2001-02-09 2002-08-23 Nippon Dempa Kogyo Co Ltd 高周波水晶発振器
JP2003258601A (ja) * 2001-12-28 2003-09-12 Seiko Epson Corp 弾性表面波装置およびそれを用いた通信機器
JP4209162B2 (ja) * 2002-09-20 2009-01-14 株式会社ニコン 押圧装置および相転移型双晶を有する水晶の製造方法
US7053522B1 (en) 2003-02-26 2006-05-30 University Of Maine System Board Of Trustees Surface acoustic wave sensor
US7285894B1 (en) 2004-02-13 2007-10-23 University Of Maine System Board Of Trustees Surface acoustic wave devices for high temperature applications
US7888842B2 (en) * 2004-02-13 2011-02-15 University Of Maine System Board Of Trustees Ultra-thin film electrodes and protective layer for high temperature device applications
US8904850B1 (en) * 2010-10-07 2014-12-09 Sandia Corporation Materials, methods and devices to detect and quantify water vapor concentrations in an atmosphere
US11112245B2 (en) * 2017-10-03 2021-09-07 Carnegie Mellon University Acousto-optic gyroscopes

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WO1997010646A1 (fr) * 1995-09-15 1997-03-20 Sawtek, Inc. Dispositif spudt saw conique pondere

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WO1996010293A1 (fr) * 1994-09-29 1996-04-04 Seiko Epson Corporation Dispositif a ondes acoustiques de surface
JP3339350B2 (ja) * 1997-02-20 2002-10-28 株式会社村田製作所 弾性表面波装置
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WO1997010646A1 (fr) * 1995-09-15 1997-03-20 Sawtek, Inc. Dispositif spudt saw conique pondere

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6031315A (en) * 1997-07-16 2000-02-29 Sawtek Inc. Optimal cut for saw devices on quartz
WO2004004119A1 (fr) * 2002-06-26 2004-01-08 Lg Innotek Co.,Ltd Substrat monocristallin et procede de decoupage de celui-ci
US7233095B2 (en) 2002-06-26 2007-06-19 Lg Innotek Co., Ltd. Single crystal substrate and cutting method thereof
WO2008046393A1 (fr) * 2006-10-16 2008-04-24 Epcos Ag Composant électroacoustique
US8247955B2 (en) 2006-10-16 2012-08-21 Epcos Ag Electroacoustic component
DE102007051314A1 (de) * 2007-10-26 2009-04-30 Epcos Ag Elektroakustisches Bauelement
DE102007051314B4 (de) * 2007-10-26 2011-12-22 Epcos Ag Elektroakustisches Bauelement

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Publication number Publication date
AU8488398A (en) 1999-02-10
US6031315A (en) 2000-02-29

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